1. Field of the Invention
The present invention relates to the angular phase registration of a plurality of rotating elements having a common drive line. More specifically, the present invention relates to multi-color rotary printing machines and the method and means therefor for resetting the several print rolls in the machine line to a known position of angular phase registration for a particular, recurrent job format.
2. Description Of The Prior Art
In a multi-color rotary printing press, each print cylinder in the machine line applies a respective image in a different color to a traveling web. It is necessary, therefore, for each print cylinder to run in close, relative phase angle registration with the other cylinders in the line. To avoid an image overlap and consequent confusion and obfuscation of the end resulting composite image, each cylinder, relative to the others, must be aligned to within approximately 0.002 in. of cylinder circumference. This magnitude of tolerance will very more or less depending on the nature of the print job performed.
Normally such printing machines are equipped with automatic control registry systems such as those described by U.S. Pat. Nos. 2,278,933; 3,594,552 and 3,701,464. The basic premise of such automatic registration systems is predicated on the application of a series of control indicia on the print web for sensors respective to each print cylinder to target on. Such sensors control automatic cylinder phase angle shifting mechanisms to align a respective print cylinder with the appropriate control indicia or indicia sequence as the web carries a precisely spaced series of such indicia past the respective print station.
Although the automatic registration control systems will maintain each print cylinder in phase registry with the other cylinder while the machine is running with a web, such automatic control systems are ineffective for initial setup of a print job.
When a machine is originally set up for a particular print format, the various print cylinder must manually be given a phase angle setting that is correct within a limited range relative to the perceptive span of the indicia sensors. Consequently, considerable time and web material is wastefully invested in simply providing the machine with a initial alignment for a particular job.
If a given machine is used to perform a multiplicity of job formats on a recurrent basis, the setup investment must be applied to each recurrence. Under such machine use circumstance, therefore, it would be desirable to record the registration relationship between the several print cylinders of a particular machine for a particular job format so that the cylinders may be returned precisely to the proper registration alignment pursuant to the record when need for a run of that particular job format recurs. It would be additionally valuable to the printer to reset the machine registry for the particular job without the presence of web in the machine to be wasted.